Study on the synergism of corrosion-resistant W-xNb alloys by angle-resolved X-ray photoelectron spectroscopy

The synergistic effect of simultaneous addition of tungsten and niobium to the sputter-deposited binary alloys of W-xNb (x = 26, 78) on exhibiting a very high corrosion-resistant activity in 12 M hydrochloric acid was studied using depth profiling technique of an angle-resolved X-ray photoelectron spectroscopy (AR-XPS) at 30℃. Both binary W-26Nb and W-78Nb alloys exhibited higher corrosion resistance properties compared with those of alloying metals, tungsten and niobium. The average corrosion rate (0.0054 - 0.0101 mm/y) noticed was nearly ten times less compared with that of W and Nb metals. Results of the depth profiling analyses of these corrosion-resistant W-xNb alloys by AR-XPS technique revealed that such corrosion action of the alloys is largely owing to the occurrence of homogeneous passive layers with W^ox and Nb⁵⁺ ions without in-depth concentration variations after immersion in 12 M hydrochloric acid, open to air, at 30℃. As a consequence, W and Nb metals acted synergistically in increasing the spontaneous passivity and the high corrosion resistance of the W-xNb deposits in 12 M hydrochloric acid.